Follow-up to T407499#11344606
We need to document the UA policy, so that users know what user agents are considered acceptable when interacting with the platform.
As a first draft we should copy the rules from the WMF (and make them as clear as possible).
A/C:
- Engineers write the policy
- Valerie to announce it the new policy
Dev Notes
- Create the policy at https://www.mediawiki.org/wiki/Wikibase/Wikibase.cloud/User-Agent_Policy